To evaluate the role played by the spatial resolution in distinguishing land cover classes in the Amazon region, different levels of spatial resolution (60, 100, 120, 200 and 250 meters) were simulated from a Landsat_5 Thematic Mapper (TM) image. Thematic maps were produced by visual interpretation from the original (30 x 30 meters) and simulated set of images. The map legend included primary forest, old and young woody secondary succession, and non-forest. The results indicated that for the discrimination between primary forest and non-forest, spatial resolution did not have great influence for pixel size equal or lower than 200 meters. The contrary was verified for the identification of old and young woody secondary vegetation due to their occurrence in small polygons. To avoid significant changes in the calculated area of these land cover types, a spatial resolution better than 100 meters is required. This result is an indication that the use of the future Brazilian remote sensing satellite (SSR-1) for secondary succession identification may be unreliable, especially for latitudes between S10° and S15° where critical areas of deforestation are located and pixel size is expected to vary within the same scene from 100 meters (S10°) to 200 meters (S15°).